http://www.iaeme.com/IJEET/index.asp 50 editor@iaeme.com International Journal of Electrical Engineering & Technology (IJEET) Volume 8, Issue 3, May-June 2017, pp. 50–60, Article ID: IJEET_08_03_005 Available online at http://www.iaeme.com/IJEET/issues.asp?JType=IJEET&VType=8&IType=3 ISSN Print: 0976-6545 and ISSN Online: 0976-6553 Journal Impact Factor (2016): 8.1891 (Calculated by GISI) www.jifactor.com © IAEME Publication SATCOM ON THE MOVE (SOTM) SYSTEM Sachin Kumar Scientist 'C', Defence Electronics Applications Laboratory (DRDO), Dehradun, India Nitin Gupta Scientist ‘E’, Defence Electronics Applications Laboratory (DRDO), Dehradun, India ABSTRACT This paper provides an overview of the Satcom On The Move (SOTM) system. Antenna servo system requirements for the SOTM have been derived and discussed. Different classes of antennas are discussed, including mechanically steered versus electronically steered with advantages & disadvantages of both. System Design has been discussed in brief. A mathematical model of dc servo motor based antenna control system is developed and step response analysis of the open/closed loop system and unit step response with a PID controller has been analyzed using MATLAB/ Simulink. Key words: Satcom on the move (SOTM), Servo control, Antenna control system, PID. Cite this Article: Sachin Kumar and Nitin Gupta, Satcom on the Move (SOTM) System. International Journal of Electrical Engineering & Technology, 8(3), 2017, pp. 50–60. http://www.iaeme.com/IJEET/issues.asp?JType=IJEET&VType=8&IType=3 1. INTRODUCTION In today’s scenario Militaries worldwide rely heavily on satellites to fulfill their communications requirements. However since modern warfare is highly asymmetric and mobile modern Military needs Satcom on the move (SOTM).The major push for Satcom on the move came during the Iraq war where both military and broadcaster crews was looking for this application to coordinate war logistics and transmit the news from the Battle zone. An SOTM control system performs the complex task of not only positioning the antenna to the desired angle but also to stabilize the antenna by cancelling out the disturbance caused by motion of the base vehicle. 2. SYSTEM REQUIREMENTS 2.1. Pointing Requirement SOTM is essentially a satellite antenna with steerable pedestal, RF modules and base-band mounted over a moving platform to establish communications on the move. Ku Band has got the advantage that the size of antenna required is relatively small which is a great advantage